In drivetrains, comprising a driving engine and at least one power takeoff, where an internal combustion engine is used as the driving engine, damper units for damping vibrations are used with a wide range of designs depending on the arising vibration conditions. Damper units function as elastic couplings that comprise at least two damper parts arranged coaxially in relation to each other, are restrictedly rotatable relative to each other in the peripheral direction, and are coupled to each other by means for transmitting torque and coupling damping.
If, in addition to the rotation of the driveshaft, torsional vibrations arise at a frequency that changes with the speed of the shaft, additional or alternative absorber arrangements are used to avoid the resulting irregular rotations. These are additional masses that are coupled by means of a spring system to the vibration system. The functioning of an absorber is based on the principle that the primary mass remains at rest at a certain excitation frequency, whereas the individual additional masses experience forced vibration. Since the excitation frequency changes with the speed of the driving engine, whereas the intrinsic frequency of the absorber remains constant, the absorption effect only occurs at certain speeds. Such an absorber is, for example, already known from the document DE 102 36 752 A1.
To absorb the effect of excitation over a broad, preferably the entire, speed range of the driving engine, speed-adaptive absorbers are provided in drivetrains, according to DE 198 31 160 A1, that can absorb torsional vibrations over a wide speed range, preferably over the entire speed range, of the driving engine by designing and arranging them so that their intrinsic frequency is proportional to the speed.
Absorbers function according to the principle of a centrifugal pendulum-type absorber in a centrifugal force field. These comprise an inertial mass support device and inertial masses oscillating thereupon about a rotary axis. When a rotary movement is introduced, the inertial masses seek to circle about the axis at a maximum distance. The torsional vibrations cause the inertial masses to execute an oscillating relative movement. Different systems are known in which the inertial masses move in a purely translational manner on a circular path of movement relative to the axis along which torque is introduced, or the path of movement has a radius of curvature that changes, at least in sections, with the increasing deflection of the inertial mass from the central position.
An arrangement of a damper unit as well as an absorber in the form of a centrifugal pendulum-type absorber device in a force-transmitting device comprising a shiftable clutch device is disclosed in the document DE 10 2006 028 556 A1. The centrifugal pendulum-type absorber device has a plurality of inertial masses that are articulated to the inertial mass support and can move relative thereto with the assistance of rollers therein.
A force-transmitting device is previously known from document DE 10 2008 057 648 A1 for transmitting power between a driving engine and a power takeoff comprising a generic damper unit that acts over the entire operating range of a driving engine and had at least two series-connectable dampers and one speed-adaptive absorber, wherein the speed-adaptive absorber is inserted between the dampers viewed at least in one direction of the flow of force through the force-transmitting device. The speed-adaptive absorber can be designed as a separately preinstallable unit. On the other hand, it is conceivable to design the speed-adaptive absorber as a component of one of the connecting elements, wherein the respective connecting element can be formed by an element of a damper of the damper unit. With such designs, the introduction of irregular rotation into the drivetrain can be reduced or avoided, especially in a direction of the flow of force that is preferably always used in the main zone of work.